QUANTUM METROLOGY AND TESTS OF FUNDAMENTAL PHYSICS WITH TRAPPED IONS - DAVIDHUME, NIST, IONSTORAGEGROUP KITP WORKSHOP MAY 3, 2021
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Quantum Metrology and Tests of Fundamental Physics with Trapped Ions David Hume, NIST, Ion Storage Group KITP Workshop May 3, 2021
Outline I. Precision measurements with trapped ions II. Tests of fundamental physics III. Extending the reach of trapped-ion measurements A. Quantum logic spectroscopy B. Improving measurement stability 5/3/2021 D. Hume
Outline I. Precision measurements with trapped ions II. Tests of fundamental physics III. Extending the reach of trapped-ion measurements A. Quantum logic spectroscopy B. Improving measurement stability 5/3/2021 D. Hume
Trapped Atomic Ions A “Single Atomic Particle Forever Floating at Rest in Free Space” Hans Dehmelt • Quantum-limited experiments • Long interaction times Hans Dehmelt 1988 Phys. Scr. 1988 102 • Small relativistic shifts • Small perturbation from EM fields + Strong, controllable Predicted resolution of 1x10-18 interactions between ions 5/3/2021 D. Hume
Principle of Optical Clocks Femtosecond Laser Drive atomic resonance 0.1 s – 10 s Laser Atomic System Frequency feedback ~0.1 Hz 11:00 am Clock frequency: ≈1015 Hz 5/3/2021 D. Hume 5
Atomic Clock Performance ( )/ 0 = 1 + + Accuracy Stability • Systematic uncertainty in clock frequency. • Average fractional frequency variations • Two types of shifts • Typically characterized by the Allan deviation: 1. Field shifts e.g. Zeeman shift and black body shift 2. Motional shifts e.g. Relativistic Doppler 1 1 ( ) ≅ 2 ∆ ⃗ � � 2 ⃗ � � = − 2 − +⋯ 2 2 2 5/3/2021 D. Hume 6
Trends in Precision Frequency Metrology In recent years, optical frequency measurements have. . . …improved more than 100x in accuracy …been applied to a vast array of atomic species …extended across continental distances + Molecules + Highly-charged ions +… …approached quantum limits in precision …found numerous applications in fundamental and applied physics M. S. Safronova, D. Budker, D. J. Kimball, D. Demille, A. Derevianko, C. W. Clark 5/3/2021 D. Hume 7
Outline I. Precision measurements with trapped ions II. Tests of fundamental physics III. Extending the reach of trapped-ion measurements A. Quantum logic spectroscopy B. Improving measurement stability 5/3/2021 D. Hume
Searching for Spacetime-Variation in Clock Frequencies ̇ = −5.3 2.3 × 10−17 /year −1.6 ± 7.9 × 10-15 1 ( ) = 2 ( ) What might cause clock frequencies to vary? • Drifts in the fundamental constants • Violations of relativity theory • Local position invariance • Lorentz invariance • Coupling to exotic particles or fields • Ultralight dark matter (mass ~ 10-22 – 10-15 eV) 5/3/2021 D. Hume 9
Boulder Atomic Clock Optical Network + ⁄ = 2.162 887 127 516 663 703(13) + ⁄ = 2.611 701 431 781 463 025(21) ⁄ = 1.207 507 039 343 337 848 2(82) Beloy et al., Nature 591, 564 (2021) 5/3/2021 D. Hume 10
New Bounds on Ultralight Dark Matter Search for oscillations in the frequency ratio Compton Frequency: Atom, transition 199Hg+, 2 1/2 → 2 5/2 - 3.0 27Al+, 1 0 → 3 0 + 0.0079 171Yb, 1 0 → 3 0 + 0.31 disfavored by astrophysical 87Sr, 1 3 +0.06 observations 0 → 0 ~ 10X improvement over several orders of magnitude in mass Depends on dark matter density (0.4 GeV/cm3), Beloy et al., Nature 591, 564 (2021) coupling constant (de) and atom-dependent sensitivity 5/3/2021 D. Hume 11
Testing Lorentz Symmetry Sanner et al., Nature 567, 204 (2019) 5/3/2021 D. Hume 12
Outline I. Precision measurements with trapped ions II. Tests of fundamental physics III. Extending the reach of trapped-ion measurements A. Quantum logic spectroscopy B. Improving measurement stability 5/3/2021 D. Hume
Quantum logic spectroscopy (QLS) Sympathetic cooling + state detection using a quantum gate 1. Cool to motional ground-state with qubit 2. Sideband pulse on Al+ (excites state-dependent motion) 3. Detect vibrational quantum with qubit QND measurement can also serve as state preparation 0.8 0.14 27Al+ 25Mg+ 27Al+ 3P D. J. Wineland, et al. 27Al+ 1S 0 Proc. 6th Symp. Freq. 0.7 0 0.12 Mean = 1.3 Mean = Stds. and Metr. (2001) Brewer et al., PRL 123, 033201 (2018) 0.6 0.1 6.9 P.O. Schmidt, et al. Probability 3P , mF = 7/2 0.5 Science 309, 749 (2005) Probability 1 0.08 F = 2, mF = -2 0.4 3P , mF = 5/2 0 0.06 25Mg+ blue 0.3 T. Rosenband, et al. PRL 98, 220801 (2007) sideband 0.04 0.2 red 27Al+ sideband 0.1 0.02 D. B. Hume, et al. PRL 99, 120502 (2007) 1S 0 0 F = 3, mF = -3 0, mF = 5/2 0 10 20 0 10 20 PMT counts Photon counts Photon counts 5/3/2021 D. Hume 14
Quantum logic spectroscopy in new systems Zeeman sublevels in the ground state of Al+ Highly-charged ions (here Ar13+) Micke et al., Nature 578, 60 (2020) Molecular ions (CaH+, MgH+) Chou et al., Science 367, 6485 (2020) Wolf et al., Nature 530, 7591 (2016) Hume et al., PRL 107 24392 (2011) 5/3/2021 D. Hume 15
An Atomic Observatory for Fundamental Physics Space clock Features: Relativity, • Broad science reach Gravitational waves • QED, fundamental constants, relativity, dark matter, gravitational Core Ensemble waves… Lattice clock MASER • Modular and extensible • Core ensemble based on proven technology Optical frequency comb • Science modules (local or remote) Free-Space connected via fiber optic or free-space Transceiver links Optical cavity .μ,Molecular Ions Ion clock dark matter… Highly-charged Ions Mobile clock . α, QED… .α,Nuclear Clock nuclear physics… Relativity, Geodesy
Outline I. Precision measurements with trapped ions II. Tests of fundamental physics III. Extending the reach of trapped-ion measurements A. Quantum logic spectroscopy B. Improving measurement stability 5/3/2021 D. Hume
Improving measurement stability Example of the Al+ optical clock Δ 1 = 2 0 Assuming: • No technical noise Measured against 171Yb clock • Uncorrelated atomic states • Global addressing Higher-stability laser Larger atom number Longer measurement (more robust operation) Brewer et al., PRL 123, 033201 (2018) 5/3/2021 D. Hume 18
Scaling up Quantum Logic Spectroscopy? … … 25Mg+ 27Al+ 5/3/2021 D. Hume
A Schrödinger Cat Interferometer Sensitive detection of ion motional displacement Motional phase-space picture 1. Qubit π/2 pulse 2. State-dependent 3. Unknown 4. Reverse SDD 5. Qubit π/2 pulse, Displacement (SDD) displacement Detect p p p p p φ φ x x x x x |↓⟩ |↑⟩ 1 |↓⟩ + |↑⟩ ↓⟩ − ⟩ |↑⟩ |+ ⟩ |− + ⟩ |+ + ⟩ −2 φ |↓⟩ + 2 φ |↑⟩ ↓ = 1 + cos 4φ 2 Unknown displacement affects qubit populations via a geometrical phase 5/3/2021 D. Hume
Demonstrations/Applications of Cat States Detecting single-photon recoils Monroe et al., Science 272, 1131 (1996) Studying motional decoherence Benhelm et al., Nat. Phot. 7, 630 (2013) Sensitive force detection Gilmore et al., PRL 118, 263602 (2017) Turchette et al., PRA 62, 053807 (2000) 5/3/2021 D. Hume
Cat state spectroscopy Mg+ MS 1 Al+ Al+ MS Mg+ MS 2 Mg+ Cooling Mg+ Detection = 0 carr. = = 2 2 ~ 1 ms ~ 20 us ~ 3 us ~ 20 us ~ 20 us ~ 100 us 3P , mF = 7/2 1 F = 2, mF = -2 rsb Mg+ rsb bsb bsb Al+ 1S F = 3, mF = -3 0, mF = 5/2 5/3/2021 D. Hume
Detection Efficiency Each qubit ion acts as an independent detector of the clock ion state State detection is more efficient at the Doppler limit 3P , mF = 7/2 1 F = 2, mF = -2 3P , mF = 5/2 0 rsb rsb bsb bsb 1S F = 3, mF = -3 0, mF = 5/2 5/3/2021 D. Hume
Reaching the Projection Noise Limit Both the spectroscopy ions and the logic ions will contribute to the projection noise NL: number of “logic ions” NS: number of “spectroscopy ions” 10 0 N L 32 ion Ramsey experiment Phase Uncertainty 1 N = 32, N = 32 2 20 L S 4 10 1/N 1/2 L S 8 m 0 , 16 L m -10 32 64 -1 128 10 -20 0 1 2 -1 -0.5 0 0.5 1 10 10 10 /2 N Number of Spectroscopy S Ions 5/3/2021 D. Hume
Outline I. Precision measurements with trapped ions II. Tests of fundamental physics III. Extending the reach of trapped-ion measurements A. Quantum logic spectroscopy B. Improving measurement stability 5/3/2021 D. Hume
Improving measurement stability Example of the Al+ optical clock Δ 1 = 2 0 Assuming: • No technical noise Measured against 171Yb clock • Uncorrelated atomic states • Global addressing Higher-stability laser Larger atom number Longer measurement (more robust operation) New techniques to mitigate laser noise Brewer et al., PRL 123, 033201 (2018) 5/3/2021 D. Hume 26
Probing Beyond the Laser Coherence Time I Decoherence free subspace Synchronized laser pulses Clock A: /2 Free evolution T /2 Detect Free evolution T Clock B: /2 2 +ф Detect Measure 2-atom parity after second /2 pulse Common-mode laser noise Clements et al. PRL 125, 243602 (2020) 5/3/2021 D. Hume 27
Probing Beyond the Laser Coherence Time IV Comparisons between different clock species? Hume PRA 93, 032138 (2016) Doerscher Comm. Phys. 3, 185 (2020) 5/3/2021 D. Hume 28
Thanks! Ion Storage Group 5/3/2021 D. Hume 29
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